The present invention relates to an inductor with multiple air-gap separations, especially to an inductor having air-gap with multiple separations to provide better electrical property.
The prior art inductor for large-current application generally has large-volume silicon-steel plates, and an air gap for increasing reluctance thereof, thus preventing saturation of the inductor. As shown in FIG. 1A and FIG. 1B, an inductor 1A is composed of an I-shaped silicon-steel plate 11a and an B-shaped silicon-steel plate 12a, and an air gap 13a with uniform separation between the I-shaped silicon-steel plate 11a and the B-shaped silicon-steel plate 12a. 
However, the air gap 13a with uniform separation has some disadvantages. If the air gap 13a is small, the inductor 1a is saturated and the inductance thereof is increased and temperature is increased in heavy load case (larger current). If the air gap 13a is large, the inductance is not enough to prevent harmonic distortion in low load case (small current). The temperature cannot be decreased to enhance efficiency in low output voltage and heavy load condition.
As can be seen from above description, the inductor having air gap with uniform separation has serious problem.
It is the object of the present invention to provide an inductor with multiple air-gap separations to overcome above problem.
To achieve above object, the present invention provides an inductor with multiple air-gap separations comprises a magnetic core and an enameled wire around the magnetic core. The magnetic core has an air gap with at least a large-gap portion and a small-gap portion. The small-gap portion provides enough inductance in case of low load input to prevent harmonic distortion. The large-gap portion provides enough inductance in case of heavy load output and low input voltage to prevent saturation and temperature rise. The air gap has a surface of stair shape, bevel shape or a curved surface to optimize the electrical property of the inductor.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: